Idle system for l.p. gas carburetors



1970' .1. R. PHIPPS IDLE SYSTEM FOR L.P. GAS CARBURETORS 2 Sheets-Sheet 1 Filed June 30. 1967 ii I] IN VLSN'I '0/ JACK R. PHIPPS ATTORNEY Nov, 10, 1970 PH'PPS 3,539,313

IDLE SYSTEM FOR L.P. GAS CARBURETORS Filed June 30, 1967 2 Sheets-Sheet 2 ZGMV 36) as L? 26 3 10:, T A! w ///A N as 42 1/ 104 qz o 94 qa. I (,6

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l VUNI ORv JACK R. PHIPPS ATTORNEY United States Patent IDLE SYSTEM FOR L.P. GAS CARBURETORS Jack R. Phipps, St. Clair Shores, Mich., assignor to The Bendix Corporation, a corporation of Delaware Continuation of application Ser. No. 650,268, June 30,

1967. This application Sept. 26, 1969, Ser. No. 863,677 Int. Cl. B01f 3/09; F02m 3/00, 7/12 U.S. Cl. 48-184 12 Claims ABSTRACT OF THE DISCLOSURE An idle system for a gaseous fuel carburetor having a fuel valve controlled by a diaphragm subjected on one side to manifold vacuum when the throttle is fully closed and subjected on both sides to manifold vacuum when the throttle has moved beyond the position of low speed operation. The diaphragm is connected to the valve by a pivoted lever which urges the valve to open position in opposition to a spring when the throttle is in closed position.

This is a continuation of SN. 650,268 filed June 30, 1967 and now abandoned.

In gaseous fuel carburetors, relatively small regulator diaphragms are often used in order to reduce the overall size of the carburetor. This, however, necessitates the use of a separate idle system or a complex, usually unreliable, mechanism operating in conjunction with the main regulator system for supplying fuel for idle, low speed and light load operation, since the main regulator system alone using the small diaphragms is not sufliciently responsive and accurate to provide the required fuel under those operating conditions. In the dual system type, the idle and main regulator systems operate independently throughout the operating range, with the exception of a relatively short transition period, during which it is desirable to blend the two systems so that a smooth transition is obtained. In the separate idle system type, the manifold vacuum is used to control the idle system in response to variations in throttle position; however, in the past this arrangement has not provided the smooth transition between the idle and main systems, and the idle system has in some instances interfered with the optimum performance of the main system by supplying a small amount of fuel to the induction passage well beyond the idle and low speed ranges. It is therefore one of the principal objects of the present invention to provide an LP. gas carburetor having separate main and idle systems, in which the transition between the idle and main systems is smooth and reliable, and neither of which systems interferes with the proper operation of the other system.

Another object of the invention is to provide a gaseous fuel carburetor utilizing relatively small main regulator diaphragms in combination with a separate idle system, in which the idle system is effectively controlled in response to the opening and closing movement of the throttle, and in which a valve in the idle system positively interrupts the flow of fuel therethrough after the operation has passed through and beyond the idle and slow speed stages.

Still another object of the invention is to provide an engine carburetor of the aforementioned type, having a relatively simple idle control mechanism which effectively controls the flow of fuel during engine idling and prevents fiow during part and wide open throttle operations, and which can be readily adjusted or otherwise regulated to obtain optimum performance during the transition period from idle and low speed operation to part and full throttle operation.

A further object is to provide an idle system for a fuel carburetor which can be easily adapted to various carburetors with little or no basic change being required, and which will operate satisfactorily under various adverse operating conditions without the necessity of any special adjustments or attention.

Additional objects and advantages of the invention will become apparent from the following description and accompanying drawings, wherein:

FIG. 1 is an elevational view of an LP. Gas Carburetor having the present idle system incorporated therein;

FIG. 2 is a cross-sectional view of the carburetor shown in FIG. 1, the section being taken on line 2-2 of FIG.1; and

FIG. 3 is a cross-sectional view of the carburetor shown in the preceding figures, the section being taken on line 33 of FIG. 1.

Referring more specifically to the drawings, numeral 10 designates generally a carburetor for an internal combustion engine having the present idle system incorporated therein, 12 indicates the main body, 14 the air intake, 16 a throttle body, and 18 an induction passage extending from the air intake 14 through the main and throttle bodies. A flange 20 is provided around the outlet end of the throttle body and contains bolt holes 22 and 24 for connecting the carburetor to the intake manifold of the engine. Throttle body 16 contains throttle 25 mounted on shaft 26 and controlled by a linkage and a lever 27 connected to the end of shaft 26. The supply of gaseous fuel is controlled in the carburetor by a main fuel regulator 28 mounted on and forming a part of main body 12.

The main fuel regulator, which may be considered conventional for the purpose of the present description, is generally the type illustrated in U.S. Pat. 3,009,794, consisting of a housing 29 having three sections 30, 31 and 32, joined rigidly together by a plurality of screws 34. The regulator contains two diaphragms, one being disposed between sections 30 and 31 and the other between sections 31 and 32, held in sealed relation with respect to the chambers therebetween by the sections on either side thereof secured together by screws 34. The induction passage of the main body contains a venturi 36, having openings 38 at the throat thereof connected to the fuel chamber in regulator 28 by a passage 40. The two diaphragms in the regulator control a metering valve 42 having a valve insert 44 in fuel inlet passage 46, and a valve element 48 engaging the valve seat on the end of insert 44. The fuel is delivered through valve 42, passage 40 to openings 38 in the venturi, and is discharged into the air flowing through the induction passage when the throttle valve is in part throttle or wide open position. While the regulator is responsive primarily to the flow of air through the venturi, it is also responsive to the air inlet pressure, and to the pressure of the gas in chamber 50 on the posterior side of valve 42. In the present carburetor shown in the drawings, the main regulator is in operation only after the throttle has 'been moved beyond the idle position and does not have any effect on the operation of the idle system.

The idle system, which is generally indicated by numeral 60, includes an idle control device 62 having a valve 64 connected to inlet passage 46 on the anterior side of valve 42 by a passage 65, and connected to the induction passage on the engine side of the throttle valve by a passage 66 and idle discharge port 68 in the side wall of the throttle body. The effective size of the idle discharge port is controlled by a needle valve 70 threadedly received in boss 72 in the side of the throttle body. The valve 64 consists of a sleeve 74 and a valve element 76 urged to its seat by a coil spring 78 reacting between the valve element and an insert 80 to constantly urge the valve toward closed position. The

valve element is moved toward open position by a lever 82 pivoted on pin 84 which is supported by the walls of housing 86.

The housing 86 of the idle control device contains a chamber 88 and a chamber 90, the two chambers being separated from one another by a diaphragm or movable member 92 clamped between sections 94 and 96 of housing '86. The diaphragm includes a stiffening member 98 having a boss 100 in the center thereof for engaging arm 101 of lever 82 for controlling valve element 76. Chamber 88 is connected to the induction passage on the engine side of the throttle by idle fuel passage 66 and discharge port 68, and to the induction passage on the air inlet side of the throttle through passage 66 and a port 102. With this arrangement, manifold vacuum is transmitted through port 68 when the throttle valve is fully closed and through ports 68 and 102 when the throttle valve is partially opened, to chamber 88 which reacts on diaphragm 92 to urge lever 82 in the direction to unseat valve element 76 and thereby admit fuel from passage 65 to passage 66 and thence through port 68 to the induction passage.

An idle cutoff system is shown in FIG. 3 in which manifold vacuum is transmitted to chamber 90 through passage 104 and port 106 adjacent the edge of throttle 25 on the air intake side thereof when the throttle is in fully open position. When the throttle is fully closed, substantially no vacuum is transmitted through port 106 and passage 104 to chamber 90; thus, the idle system is operated directly by manifold vacuum transmitted to chamber 88 through passage 66 and idle discharge port 68. As the throttle is moved toward opened position, the leading edge of the throttle passes port 102, thereby subjecting this port to manifold vacuum which is transmitted through passage 66 to chamber 88. On further opening of the throttle, port 106 is also subjected to manifold vacuum which is transmitted through passage 104 to chamber 90, thus tending to equalize the pressures in the chambers 88 and 90 so that the force exerted on lever 82 by the diaphragm is diminished to the point where spring 78 can seat valve element 76 and interrupting the flow of fuel through the idle system. The precise point at which the idle cutoff valve 64 operates to interrupt the flow of fuel through the idle system can be predetermined by properly positioning ports 102 and 106 relative to the leading edge of throttle 25. Further control may be obtained by providing a bleed port in passage 104 or chamber 90 to reduce the effect of the vacuum transmitted from the induction passage through passage 104 to chamber 90.

In the operation of the carburetor embodying the present idle system, starting with the engine running and the throttle valve closed, manifold vacuum is transmitted through idle port 68, passage 66 and chamber 88, which reacts on diaphragm 92, causing the diaphragm to move toward chamber 88, i.e. upwardly as viewed in FIGS. 2 and 3, thereby moving lever 82 in the direction to open valve 64. With the opening of valve 64 gaseous fuel flows from supply passage 46 through passage 65, through valve 64 and passage 66 to idle discharge port 68. With the throttle valve fully closed, the pressure in chamber 90 is substantially atmospheric, and hence, creates sufiicient differential in pressure across the diaphragm to effectively hold the valve element 76 off its seat in opposition to spring 78 as long as the throttle valve remains in its fully closed position, thus permitting the idle system to function without interference from control valve 64. As throttle 25 is moved toward open position, the leading edge passes port 106, thereby transmitting manifold vacuum through passage 104 to chamber 90, and thus equalizing the pressure across diaphragm 92. With the pressures in chambers 88 and 90 substantially equal, the spring 78 is able to exert sufficient force on valve element 76 to close valve 64 and interrupt the flow of fuel through the idle system. As long as the throttle is in part or full throttle position, the pressures in chambers 88 and 90 remain substantially equal, thus Permitting the spring 78 to hold valve 64 in fully closed position, and thereby preventing the idle system from inadvertently becoming operable at some stage of the operation beyond normal idling or slow speed states. When the throttle valve has been moved to the position beyond ports 102 and 106, the main regulator system becomes fully operative and controls main metering valve 42 to provide the proper amount of gaseous fuel to the carburetor through the discharge ports 38 in the venturi. The main regulator continues to provide the fuel to satisfy engine operating requirements until the throttle has been moved to near closed position. Upon the return of throttle to closed position, port 106 is again exposed to substantially atmospheric pressure and idle discharge port 68 is subjected to manifold vacuum. The pressure in chamber 88 is substantialy reduced and the pressure in chamber 90 is increased, thereby creating sufficient differential across the diaphragm to move lever 82 in the counterclockwise direction, as viewed in FIG. 2, and unseat valve element 76. This places the idle system in full operation until the throttle is again opened or the engine turned off.

While only one embodiment of the present idle system has been described in detail herein, various changes and modifications may be made without departing from the scope of the invention.

I claim:

i1. In a gaseous fuel carburetor having an induction passage with a throttle therein, a main fuel regulator and a fuel supply conduit: an idle system comprising a fuel control valve, a spring urging said valve to closed position, a housing having two chambers, a diaphragm separating said chambers, a passage connecting said valve with said fuel supply conduit, a passage connecting said valve and one of said chambers with the induction passage on the engine side of the throttle, a passage connecting the other of said chambers with the induction passage on the air inlet side of the throttle in close proximity to the leading edge thereof, and a means connecting said diaphragm with said valve for opening said valve when the throttle is closed beyond the point at which said last mentioned passage is connected to the induction passage.

2. An idle system for a gaseous fuel carburetor as defined in claim 1 in which the passage connecting the valve with the fuel supply conduit is connected to said fuel conduit anterior to the main fuel regulator.

3. An idle system for a gaseous fuel carburetor as derfined in claim 1 in which the means connecting the diaphragm with said valve includes a pivoted lever having an arm connected to the valve and another arm connected to the diaphragm whereby movement of the diaphragm toward the chamber communicating with the induction passage on the engine side of the throttle moves said valve toward open position in opposition to said spring.

4. An idle system for a gaseous fuel carburetor as defined in claim 1 in which the passage connecting the valve to the induction passage on the engine side of the throttle includes a port connecting the same passage to the induction passage on the air intake side of the throttle when the throttle is in closed position.

5. An idle system for a gaseous fuel carburetor as defined in claim 4 in which the passages connecting the two chambers to the induction passage adjacent the throttle valve are so positioned with respect to the throttle in the induction passage that the pressures in the two chambers become substantially equalized upon the movement of the throttle toward open position beyond idle and slow engine speed.

6. An idle system for a gaseous fuel carburetor as defined in claim 4 in which the means connecting the diaphragm with said valve includes a pivoted lever having an arm connected to the valve and another arm connected to d1? diaphragm whereby movement of the diaphragm toward the chamber communicating with the induction passage on the engine side of the throttle moves said valve toward open position in opposition to said spring.

7. An idle system for a gaseous fuel carburetor as defined in claim 6 in which the passage connecting the valve with the fuel supply conduit is connected to said fuel supply conduit anterior to the main fuel regulator.

8. In a gaseous fuel carburetor having an induction passage with a throttle therein, a main fuel regulator adapted to be connected to a fuel supply; an idle system comprising a fuel control valve having an inlet adapted to be connected to said fuel supply and an outlet connected to the induction passage on the engine side of said throttle; a housing; a member cooperating with said housing to provide two chambers which is movable in response to pressure differences between said chambers, means subjecting one of said chambers to the pressure in the induction passage on the engine side of the throttle; means subjecting the other of said chambers to the pressure in the induction passage on the air inlet side of the throttle in close proximity thereof when said throttle is closed; and means, connecting said movable member with said valve, for opening said valve in response to a pressure difference between said chambers caused by said throttle being in the closed position, and for closing said valve in response to a lower pressure difference between said chambers when said throttle is opened a predetermined amount.

9. In gaseous fuel carburetor having an induction passage with a throttle therein, a main fuel regulator adapted to be connected to a fuel supply; an idle system comprising a fuel control valve having an inlet adapted to be connected to said fuel supply and an outlet connected to the induction passage on the engine side of said throttle; a housing; a member cooperating with said housing to provide two chambers which is movable in response to pressure differences between said chambers, means subjecting one of said chambers to the pressure in the induction passage on the engine side of the throttle; a passage connecting the other of said chambers with the induction passage on the air inlet side of the throttle in close proximity to the leading edge thereof when said throttle is closed; and means, connecting said movable member with said valve, for opening said valve when said throttle is closed beyond the point at Which said last mentioned passage is connected to the induction passage, and for closing said valve when said throttle is opened beyond the point at which said last mentioned passage is connected to the induction passage.

10. The gaseous carburetor of claim 9 wherein said idle system fuel control valve outlet and said one of said chambers are connected to the induction passage on the engine side of the throttle by a single passage, said single passage constituting said means for subjecting said one chamber to the pressure in the induction passage on the engine side of the throttle.

11. A gaseous fuel carburetor of claim 9 wherein said movable member is a diaphragm.

12. The gaseous carburetor of claim 1'1 wherein said idle system fuel control valve outlet and said one of said chambers are connected to the induction passage on the engine side of the throttle by a single passage, said single passage constituting said means for subjecting said one chamber to the pressure in the induction passage on the engine side of the throttle.

References Cited UNITED STATES PATENTS 2,774,582 12/1956 Bracke. 2,795,494 6/1957 Ensign 48-184 2,801,621 8/1957 Anderson et al. 2,871,841 2/1959 Goodridge et a1. 123119 2,984,465 5/1961 Hazzard. 3,009,794 11/1961 Barfod 48-184 3,037,751 6/ 1962 Phillips. 3,174,732 3/1965 Brown. 3,181,843 5/1965 Brown et al.

MORRIS O. WOLK, Primary Examiner B. S. RIOHMAN, Assistant Examiner US. Cl. X.R. 

